I have 4 PayPal feeds, each with a different price and purpose. When checking out using a PayPal enabled form the product that shows on PayPal seems to be randomly chosen between all the feeds.
Sometimes the correct product shows in PayPal and sometimes it is the product from one of the other feeds.
My issues seems to be similar to this one but subtly different:
http://www.gravityhelp.com/forums/topic/paypal-not-receiving-the-correct-amount
PayPal is receiving an amount it's just not always the correct amount.
Form:
http://cl.ly/image/1h3h430x370s
PayPal (showing the PayPal feed for another product):
http://cl.ly/image/1w23163U0B1F